1. Field of the Invention
The present invention relates to a laminator film which is preventive of forming creases, air bubbles and air pockets upon lamination and, more particularly, to a laminator film which has a plurality of continuous, fine grooves close together to its contact surface, through which the air between the contact surface and a target film can be guided out when laminating the film on the target film.
2. Description of the Prior Art
For a lamination technique with which a thermoplastic film or coat is laminated on a target film, the adhesiveness between the film or coat and the target film is a very important factor. Prevention of air accumulation between the film or coat and the target film is also critical to the technique. In other words, a good laminated product cannot be expected without excellent adhesiveness and exclusion of air accumulation between a laminator film and a target film.
If air accumulates between a film or coat and a target film when laminating, creases, air bubbles or even air pockets occur in the resulting laminated products, making the products poor in appearance. Air bubbles, even if fine, deteriorate the transparency and vividness of high quality printed matters. Air pockets, which are distinct from air bubbles in size, make the film or coat come off the target film as well as move around from place to place, resulting in a great decrease in the adhesiveness between the film or coat and the target film.
Conventionally, in order to avoid the creases, air bubbles or air pockets resulting from air accumulation, a laminator film is laminated on a target film with the aid of a pair of engaged rollers. The two sheets enter the space between the rollers in such a way that the angle between the laminator film and the target film may be as large as possible.
Another means to prevent air accumulation is corona discharge. Laminator films are subjected to corona discharge to form protrusions on the laminating surface of the laminator film or fine holes which penetrate the films.
Formation of an embossed surface on a laminator film has been used to prevent the occurrence of the creases and air pockets upon its lamination. In one method, an embossed surface is made by passing a thermoplastic film overlaid by a woven cloth through an interspace between a pair of hot engaged rollers and by then removing the woven cloth.
However, the discontinuous fine holes or protrusions formed on the contact surface of a laminator film by corona discharge or embossing, respectively, cannot continuously guide the air out between the contact surface of the film and the target film, so that creases or air pockets cannot be efficiently prevented with these methods.